Hb Knossos: HBB:c.82G>T Associated with HBB:c.315+1G>A Beta Zero Mutation Causes Thalassemia Intermedia

Hb Knossos (HBB: c.82G > T), β-globin CD 5 (-CT) (HBB: c.17_18delCT) and δ-globin CD 59 (-a) (HBD: c.179delA) mutations in a Syrian patient with β-thalassemia intermedia

Background

Beta thalassemia (β-thal) is an inherited hemoglobin disorder characterized by reduced synthesis of the hemoglobin that results in microcytic hypochromic anemia. β-Thalassemia intermedia (TI) is a clinical term of intermediate gravity between the carrier state and β-thalassemia major (β -TM).

Case presentation

We describe a 12-year-old male proband originating from Al-Quneitra province - southwest Syria. Hematological investigations revealed, pallor and anemia (Hb 9 g/dl). The mean cell volume (MCV) 64 fL; mean cell hemoglobin (MCH) 21.8 pg. Capillary electrophoresis (CE) electropherogram revealed low level of Hb A1 (36.2%), high level of Hb F (62.2%) and low level of Hb A2 (1.6%). The proband requires blood transfusion occasionally. Direct DNA sequencing and Polymerase chain reaction-restriction fragment length polymorphism (PCR/RFLP) for mutations detection were used. The molecular analysis revealed the presence of rare β⁺ Hb Knossos codon 27 (G > T) (HBB: c.82G > T) variant associated with β⁰ codon 5 [−CT] (HBB: c.17_18delCT) mutation in beta-globin (β-globin) gene and δ⁰ codon 59 [−A] (HBD: c.179delA) mutation in delta-globin (δ-globin) gene. The proband tested negative for the common deletional forms of alpha thalassemia (α-thal). Polymorphism of the Xmn-I locus (HBG2: c.-211C > T) revealed that the proband had a homozygous [TT] for Xmn-1 locus.

Conclusions

To our knowledge, this is the first report of beta thalassemia intermedia due to combination of Hb Knossos /codon 5 [−CT] associated with δ⁰ codon 59 [−A] in Syrian patient. On the other hand, in Syria, β-thal carriers who have low level of Hb A2 due to decreased δ-chain production, different δ-thal gene mutations must be screened to avoid the failure diagnosis of β-thal disease.

Identification of a Rare β(0)-Thalassemia Mutation, Codon 54 (-T) (HBB: c.165delT) in an Iranian Family

β-Thalassemia (β-thal) is the most widespread autosomal recessive disorder worldwide. The present study describes a very rare β-globin gene mutation, codon 54 (-T) (HBB: c.165delT), in a family from northern Iran. Nucleotide sequencing of amplified DNA obtained from a 28-year-old man revealed a deletion (-T) at codon 54 of the β-globin gene that results in a nonsense sequence at codon 60 and inphase termination at codon 59. Moreover, the haplotype combination of six different restriction enzyme sites in the β-globin cluster was determined for this mutation. To the best of our knowledge, this is the second article reporting the codon 54 mutation worldwide and the first report of this mutation in the Iranian population, emphasizing the high heterogeneity of this population.